Resin composition

ABSTRACT

A resin composition with excellent anti-blocking properties and transparency which comprises a polyolefin resin admixed with a fine, modified inorganic powder which is prepared by mechanochemically modifying the fresh surface of an inorganic powder with a surface modifier selected from the group consisting of fatty acids, metal salts of fatty acids, aliphatic alcohols, aliphatic amides and aliphatic amines.

United States Patent 1191 Arai et al.

1451 Apr. 9, 1974 RESIN COMPOSITION [75] Inventors: Masakazu Arai; Junichi Yasuda,

both of Yokkaichi, Japan [73] Assignee: Mitsubishi PetrochemicalCompany,

Tokyo, Japan 22 Filed: Nov. 13, 1972 [21] App], No.: 305,711

[30] Foreign Application Priority Data Nov. 12, 1971 Japan...' 46-90457 [52] US. Cl ..-.260/23 H, 260/32.6 PQ, 260/33.4 PQ, 260/41 A, 260/94.9 GB

[5i] Int. Cl. C08f 19/14 [58] Field of Search 260/23 H, 94.9 GB, 93.7, 260/41 A, 32.6 PQ, 33.4 PQ

[56] References Cited UNITED STATES PATENTS 3,463,751 8/1969 Hasegawa ..260/23H 3,591,540 7/l97l Praskach 260/23 H Primary ExaminerDonald E. Czaja Assistant Examiner-William E. Parker Attorney, Agent, or FirmOblon, Fisher, Spivak, Mc Clelland & Maier [57] ABSTRACT 5 Claims, No Drawings 1 RESIN COMPOSITION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a resin composition possessing excellent anti-blocking properties and transparency.

2. Description Of The Priorv Art It has been known to prevent blocking in polyolefin films by admixing polyolefin resins with fine inorganic powders. However, these films have the disadvantage of a decreased transparency. If an inorganic powder such as a pigment is admixed with a resin, metal containing soaps such as aluminum, zinc or calcium stearates have been added to the resin composition in order to improve the dispersibility of the inorganic powders. Specifically, calcium carbonate has been modified with soap to improve its dispersibility in rubber and to reinforce the rubber. Titanium oxide has been modified and silica gel has been modified with an alcohol, an organic silicon compound or a hydrogen fluoride to improve its dispersibility in an organic compound.

Studies were conducted in order to provide an antiblocking effect in olefin resin by modifying the surfaces of inorganic powders admixed with the resins. However, while the dispersibility of the inorganic powders in the resins had improved, the transparency of the resulting compositions decreased.

Heretofore, films of polyolefins such as low density polyethylene and polypropylene have had excellent transparency, moisture resistance, heat sealing effects, oil resistance and strength. Thus, large amounts of these films have been used as packaging materials for food and fabrics. For these uses, a high degree of transparency of the films has been required. However, as the transparency of these films has been improved, the disadvantageous property of blocking occurs. Blocking results in a loss of efficiency in operational steps such as the slitting step, the printing step, the bag forming step and the mouth opening step for both tubular films and flat films. Sometimes, the films are torn. Thus, in order to improve the blocking properties of films, fine inorganic powders have been admixed with polyolefin resins.

Prior art processes have included the addition of aliphatic amides such as oleic amide to the polyolefin resin. When the amount of aliphatic amide admixed is too great, the resulting films becomewhite upon aging because of the migration of the aliphatic amides to the surface of the films. In addition, the adhesiveness of applied printing inks decreases. Thus, the amount of aliphatic'amide admixed with the resin must be limited. Improvements in the blocking properties of this film has been mainly provided by the addition of fine inorganic powders to the resins. However, while the addition of fine inorganic powders to the resin improves the blocking properties of these films, it also causes a concommitant loss of transparency in the films.

Anti-electrostatic films and non-water drop films have high blocking properties. Thus, it is necessary to add larger amounts of fine inorganic powders to these films in order to prevent blocking. However, these films lose their transparency upon incorporation of the inorganic powders. In view of the blocking problems associated with polyolefin resins, a need exists for suitable additives which prevent blocking in these films,'while at the same time resulting in films which possess good transparency.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a polyolefin resin composition which has excellent transparency and exhibits good anti-blocking characteristics.

It is another object of this invention to provide a polyolefin resin composition with excellent transparency and anti-blocking characteristics by incorporation of a fine inorganic powder prepared by an economical process in the resin composition.

These objects and other objects of this invention, as hereinafter will become apparent, can be attained by a resin composition comprising a polyolefin resin and an inorganic powder modified by a mechano-chemical process wherein an unmodified inorganic powder or a powder mass with a particle size larger than that of the modified powder is admixed with a modifier selected from the group consisting of fatty acids, metal salts of fatty acids, aliphatic alcohols, aliphatic amides, and aliphatic amines, and crushed into a fine powder. The sur* face of the resulting inorganic powder is modified and possesses hydrophobic properties.

DESCRIPTION OF PREFERRED EMBODIMENTS (I) silica gel,

(2) anhydrous silicic acid,

(3) silicic acid hydrate,

(4) calcium silicate hydrate. (5) aluminum silicate hydrate, (6) calcium carbonate,

(7) barium carbonate, (8) calcium sulfate, (9) barium sulfate, (10) talc,

(l l) clay The unmodified inorganic powder or powder mass is crushed with a modifier in a conventional crusher such as a vibration mill, a pot mill, a speed line mill, or a colloid mill to yield a fine, modified, inorganic'powder. The average particle size of the modified inorganic powder is in the range of 0.l-l5p., preferably 1-6p. if the powder is to be used in non-stretched films or in molded articles other than films. On the other hand, the average particle size is less than 300 mu, preferably 10-200 mp., if the powder is to be used in stretched films.

If the average particle, size of the inorganic powder incorporated in the film is greater than the upper limit, the appearance of the film deteriorates. If the average particle size of the inorganic powder is less than the lower limit, the anti-blocking characteristic of the resulting film is diminished.

The modifiers of this invention are aliphatic compounds possessing polar groups which have good affinity for the inorganic powder or powder mass. Suitable modifiers include fatty acids, metal salts of fatty acids, aliphatic alcohols, aliphatic amides and aliphatic amines, and the like. Polar groups in the aliphatic compounds include OH, COOH, .COOMe, -CONH NH;, and the like. The aliphatic residues of the modifiers have a high affinity for the polyolefin resins. Straight chain aliphatic residues rather than cyclic aliphatic residues have a greater dispersibility in' the polyolefin resins. Preferably, compounds containing more than ten carbon atoms per chain are used and are readily available.

The amount of modifier admixed with the inorganic powder is in the range of 0. 1-30 weight percent, preferably l-l weight percent, of the weight of inorganic powder. If the amount used is less than 0.1 weight percent, the desired effect of this invention is not found. if the amount used is more than 30 weight percent, no

greater improvements result over those already observed for the increased amount of modifier used.

The following is a list of suitable, specific modifiers useful in this invention.

1. Fatty acids and Metal Salts of Fatty acids Saturated fatty acids ranging from C (capric acid) to C lignoceric acid) are used. Preferably, readily available palmitic acid (C and stearic acid (C are used. Unsaturated fatty acids with greater than -1 8 carbon atoms, preferably erucic acid (C are used.

' Suitable metal cations for the fatty acid salts include:

monovalent metals (Li,Na,K),

divalent metals (Mg,Ca,Ba,Zn,Cd), trivalent metals (Al), and te travalent metals (Pb).

Preferably, monovalent and divalent metal salts of the fatty acids are used. 2. Aliphatic alcohols Saturated alcohols ranging from C (decanol) to C (eicosanol) are used. Preferably, tetradecanol (C 4), hexadecanol (C and octadecanol (C are used. Unsaturated alcohols include alcohols such as oleyl alcohol. Polyalcohols include glycerine polyethyleneglycol, polypropyleneglycol, and the like. 3. Aliphatic'amides 1 Saturated amides ranging from C (undecylamide to- C (docosylamide) are used. Preferably, readily available stearylamide is used. Unsaturated amides include readily available oleylamide (C ethylene bisaliphatic amides, and polyoxyethylene alkylamides such as N,N-bis( Z-hydroxyethyl )alkylamides 4. Aliphatic amines 1 Preferably, C (tetradecyl amine) to C (docosyl amine) aliphatic amines are used. Polyoxyethylene alkylamines such as N,N-bis( 2-hydroxyethyl)alkylamines (C -C 3) can also be used. I

In the process of this invention, the inorganic powder or powder mass is treated with a surface modifier. Suitable methods of treatment include solid phase treatmerits, liquid phase treatments, vapor phase treatments, and the like. The solid phase treatment method can be accomplished by admixing an inorganic powder mass or coarse powder with a surface modifier, and then crushing'the mixture in a mill to provide mechanochemical reaction between the reactants. The liquid phase treatment method can be accomplished by treating the inorganic powder mass or coarse powder with an aqueous solution or a solvent solution of the surface modifier, and then crushing the inorganic powder mass or coarse powder to provide a mechano-chemical reaction between the reactants. The vapor phase treatment method can be accomplished by vaporizing an aliphatic amine, an aliphatic alcohol or a fatty acid, adsorbing the vapors on the surface of the inorganic powder mass or coarse powder, and crushing the treated solid residue. Another treatment method can be accomplished by adding the surface modifier with a crystallized mass of inorganic material, and crushing the treated inorganic material. The inorganic powder mass or coarse powder should be crushed to a fine powder in order to form a fresh, large surface area to which the surface modifier is mechanochemically coated.

The modified fine inorganic powder prepared by crushing the inorganic material with a surface modifier is blended with a polyolefin resin in amounts ranging from 0.0l-2.0 weight percent, preferably 0.05-O.5O weight percent of the amount of resin. If less than 0.01 weight percent modified powder is used, the desired antiblocking effect is not found in the resin product. On the other hand, if more than 2.0 weight percent modifled inorganic powder is used, besides being uneconomical, no increased antiblocking effect is observed in the resin product corresponding to the increased amount of modifier employed. If the amount of modifled inorganic powder added to the polyolefin resin is too large, the transparency of the resin composition is decreased.

Blending of the modif ed inorganic powder with the polyolefin resin can be accomplished with a conventional kneader for plastics, a screw blender, or the like. The following description outlines the various processes useful for the preparation of films using a polyolefin resin composition of this invention.

1. Preparation of tubular films polypropylene:

Tubular polypropylene film apparatus manufactured by Kawada Seisaku-sho K.K.

Apparatus:

Diameter of extruder 45 mm Die lOO mm Screw rotation lOO rpm. Resin temperature, 230C Distance between V die and air ring lOO rnm Distance between 7 die and water cooled V ring 300 mm Film thickness 30p. Blow rate L4 Take up speed 20 m/min.

2. Preparation of biaxial stretched polypropylene films:

Longitudinal stretch: Rapidly stretched 500% by a I peripheral difl'erent velocity of the hot roller at l35C. Stretched 600% in a tenter at l60C and with a heat treatment at C for 5 seconds.

Vertical stretch Thickness of film 3. Preparation of low density tubular polyethylene films:

Having now generally described the invention, a' further understanding can be attained by reference to certain specific examples, which are provided for purposes of illustration only and are not intended to be limiting Apparatus Tubular film apparatus 5 in any manner unless otherwise specified.

manufactured by Mitsubishi Jyuko K.K. EXAMPLE I Diameter of cxtruder :8 mm A 500 g quantity of silica gel with an average particle Screw rotation rpm. Resin temperature 160C diameter of 5 mm was admixed with 50 g of calcium Distance between stearate. The mixture was charged into a l0 liter pot die l 65 mm mill, crushed in air at 20C at the rate of 50 rpm for 48 Blast line height 280 mm o Blow rate 1.5 hours, and then dried for 1 minute at 350 C to yield a Take u speed Zo n/min. modified fine silica gel powder with an average particle diameter of 3 ,u. A sample. for reference was obtained by the same preparaton Cast films process except that calcium stearate was not used. A

Apparatus Cast film apparatus manufactured 0.40 weight percent quantity Of the resulting fine silica f by Mdem Machmfiy gel powder was admixed with polypropylene powder 3123: 0 90 mm manufactured by Mitsubishi Petrochemical Company Screw rotation 75 rpm. (melt index 8.0 g/ 10 min; n-heptane extraction residue gf ig ff fif f 245 c 96.0 weight percent) together with 0.05 weight pertemperature C cent 3.5 di-tert-butyl paracresol, 0.03weight percent b t v d z mamffld tetrakis [methylene-3-(3,5 di-tert-butyl-4- jj g an m hydroxyphenl) propanoate] methane, and 0.25 weight quench roller 25 percent oleic amide. v mmacmg The powdery mixture was blended for 3 min by film to quench roller) Thickness of mm means of a Super mixer manufactured by Kawada Take p snvcd 85m/min- Seisaku-sho K.K., and melt-extruded at 220C by a granulator with a 40 mm extrusion diameter to yield a The qualities of the films prepared by these processes granular composition. To the granular composition was are evaluated by the following testing methods: added unmodified fine silica gel and 10 weight percent calcium stearate based on the weight of silica gel. The Haze 0f the films Was measured by the S D mixture was blended and mixed in accordance with the 1003-6] method. Transparency of the films was calcu- 3 above preparation (Table I, No. 2) lated as percentage units. 5 In accordance with preparation (1), a granular com- 2. Antiblocking Properties position was extruded in the form of a tubular film in Two freshly prepared sheets of film (300X300 mm) the polypropylene tubular film apparatus manufacare plied and a weight of 50 g/cm is applied to the tured by Kawada Seisaku-sho K.K. with an extrusion plied films at 40C for 24 hours. A test piece with a 20 40 diameter of mm. The conditions of film formation mm width and a 110 mm length (contacting area 20-50 are clearly outlined in preparation (I). The transpar- 7 mm) is cutand the maximum weight required to peel ency, anti-blocking properties and static friction coeffithe upper film from the lower film is measured by a cient characteristics of the resulting polypropylene film friction coefficient tester manufactured to Toyo Seiki are shown in Table l.

" "TKELE I No. Fine silica Melt Melt Clou- Block- Coefficient gel powder index index diness ing of static pellet film (Haze) Properfriction (g/lO min) (g/IO min) ty (g/ 10 cm) Reference 1 Unmodified 9.0 12.1 4.l 280 0.19 Reference 2 Ca-stearate 9.1 l2.0 3.5 290 0.18

blend Invention 3 Modified by 9.0 12.0 2.0 280 0.17

Ca-stearate l(.l(.. The peeling velocity of the film is 150 mm/min. EXAMPLE 2 v The antiblocking property is based on a unit of g/l0 in accordance with the process of Example 1, 500 g cm of silica gel were admixed with 50 g each of stearic 3. Coefficient of static friction v acid, hexadecanol, stearic amide, stearylamine, N, N- The coefficient of static friction is measured by the bis(2-hydroxyethyl) stearylamide and N, N-bis (2- ASTM D 1894 method and shows the slipping properhydroxyethyl) stearylamine, and the mixture was ties of the films. crushed to yield a' modified fine powder. The modified 4. Melt index The melt index is measured by the ASTM D 1238 method.

fine powder was admixed with polypropylene powder and tested. The results of the test are shown in TABLE II.

7 8 TABLE 11 No. Fine silica Melt Melt Clou- Block- Coefficient gel powder index index diness 111g of static pellet film (Haze) Properfriction 110 min) (8/10 min) ty (g/IO cm) Reference 1 Unmodified 9.0 12.1 4.1 280 0.19 Invention 2 Modified by 9.5 15.5 1.9 300 0.18

stcaric acid invention 3 Modified by 9.1 12.0 2.9 270 0.19

Y hexadecanol invention 4 Modified by 9.0 12.1 3.0 250 0.17

stearylamide Invention 5 Modified by 9.0 13.6 2.6 290 0.16

srearylamine Invention 6 Modified by 9.1 12.3 2.5 290 0.18

. bis( Z-hydroxyethyl) stearylamide Invention 7 Modified by 9.3 12.5 2.4 280 0.17

. bisfiZ-hydroxyethyl) stcarylamine EXAMPLE 3 EXAMPLE 4 The modified fine s1l1ca gel powder prepared in ac- The modlfied fine s1l1ca gel powder prepared in accordance with the procedure of Example 1, was used cordance with Example 1, and the unmodified fine silin a polypropylene cast (T-die) film, and the unmodiica gel powder were separately admixed with portions fied powder was used as a reference. A 0.10 weight perof low density polyethylene. A 0.1 weight percent amocent quantity of the fine silica gel powder was admixed unt of tine silica gel powder was admixed with low denwith polypropylene powder manufactured by Mitsity polyethylene manufactured by Mitsubishi Tetrosubishi Petrochemical Company (melt index 6.5 g/l() Che Cal Company t n x 1.7 g/ 10 l, ensity min., n-heptane extraction residue 96.0 weight percent. 0.924 g/cc) together with 0.05 weight percent 3,5-di- A 0.10 weight percent amount of 3,5-di-tert-butyl paratert-butyl paracresol and 0.10 weight percent oleic amcresol, 0.05 weight percent tetrakis [methylene-3-(3,5- 3O ide, and the mixture was extruded from a granulator to di-tert-butyl-4- hydroxyphenyl) propanoate] methane, yield a granular composition. In accordance with pre- 0.08 weight percent erucic amide and 0.05 weight perparative procedure (3), a tubular film was prepared cent calcium stearate were added to the mixture. The from the composition by an inflation film apparatus powdered mixture was blended for 3 min. in a Super manufactured by Mitsubishi .lyuko K.K. with an extrumixer manufactured by Kawada SeisakU-sho K.l(., sion diameter of mm. The properties of the resulting and melt-extruded at 220C in a granulator with an exfilm are shown in TABLE IV.

. no i h 7 A N .r- M- f -a- No. Fine silica Melt Meit Clou- Block- Coefficient gel powder index index diness ing of static pellet film (Haze) property friction (g/10 min) (8/10 min) (96) (g/lO cm) Reference 1' Unmodified 1.8 1.8 8.4 0.07 lnvention 2 M9$1ifigd by 1.7 1.7 7.0 0.06

Ca-stearate V (08165 diameter ib mrn to yield a gainiar'eaapbsi EXAMPLE 5 tion. In accordance with preparation (4), the granular A 500 g quantity of silicic acid hydrate with an avercomposition was extruded to form a flat'film'in the cast age di eter of 15 mm was admixed with barium steafilm apparatus manufactured by Modern Machinery rate, and the mixture was charged to a 10 liter pot mill K.K. with an extrusion diameter of mm. The condiwhere i was sh d i i at 20C t th rate f 50 tions Of film formation are clearly outlined in prepararpm, for 48 hours The resulting composition was dried tive procedure t results are Shown in TABLE 55 for 1 minute to yield a modified fine silicic acid powder 111. g Y v with an average particle diameter of 30 mp. A refer- TABLE 111 No. Fine silica Melt Melt Clou- Block- Coefficient gel powder index index diness ing of static pellet film (Haze) Properfriction (3110 min) (g/lO min) .ty

(8/ Reference 1 mm 7.3 13.5 3.2 260 0.41

lnvention 2 M i ied... 72 v 13.3 2.3 270 0.47

Ca-stearate V ence sample was obtained by the same process except without the addition of barium stearate. A 0.10 weight percent quantity of the resulting fine silicic acid powder was admixed with polypropylene powder manufacchanges and modifications can be made thereto without departing from the spirit or scope of the invention as set forth herein.

What is claimed as new and desired to be secured by tured by Mitsubishi Petrochemical Company (melt Letters Patent of the United States is: index 1.2 g/IO min.; n-heptane extraction residue 95.0 1. A resin composition having a high transparency Weig t perc n together with 020 Weight p r and antiblocking properties which comprises a polyoledi-tert-butyl paracresol, 0.05 weight percent tetrakis fin re in selected from the group consisting of pglygthmethylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl) ylene, polypropylene, copolymers of propylene and propanoate] methane, 0.05 W igh pe cent C u ,B-olefins, copolymers of ethylene-vinylacetate and stearate and 0.06 weight percent eru C am e ethylene-acrylic acid esters admixed with a modified P mixture was blended for 3 in a p fine inorganic powder, which powder is prepared by miXer was extruded at 230C from a grahulator with mechano-chemically bonding the fresh surface of an extrusion diameter 0f 40 mm to yield a gr inorganic powder selected from the group consisting of p i nn accordance i p p r silica gel, anhydrous silicic acid, silicic acid hydrate, employes a biaxially stretched fihh apparatus f calcium silicate hydrate, aluminum silicate hydrate, hired y Mitsubishi Jyuko with an extrusion diamcalcium carbonate, barium carbonate, calcium sulfate, etel' of 115 mm, a biaxial stretched mm with a thick barium sulfate, talc and clay with a surface modifier seof h was P p The Propenies of the result lected from the group'consisting of C -C fatty acids, ihg mm are Show" in TABLE 20 metal salts of said fatty acids, C C aliphatic alco- TABLE v N0 Fine silicic Melt Melt Clou- Block- Coefficient acid powder index index diness ing of static pellet film (Haze) properfriction (g/lOmin) (g/lOmin) ty (g/lOcm Reference Unmodified 1.4 2.0 1.5 380 0.55 Invention 2 Modified by L5 2.1 0.8 400 0.57

Ba-Stearate EXAMPL 6 hols, C -C aliphatic amides and C C aliphatic Into a 10 liter pot mill was charged 5 liters of a 0.50% amlhes' D aqueous sodium stearate solution and 500 g of calcium h Q h clam wherem Sald carbonate with an average particle diameter of 10p. (5 orgahlc Powder afhhlxed'wlth welght p f h wt sodium stearate based on the powder) was added. of $3110 Surface modlfier j' Oh the wclght of 531d After Scaling the apparatus, the mixturc was crushed organ1cpowdcr,und whercm said polyolefin resin 21dfor 24 hours at the rate of 50 rpm. The contents of the mlxed wlih 9 weight Percem of Said modified mill were centrifuged to separate the aqueous solution fine inorganic P der based on the weight of said polyfrom the solids. The powder was dried at 105C for 24 0 olefin resin. hours and then dried under a reduced pressure of 760 3- Th r sin Composition of claim 1, wherein said mmHg f 4 hours A 500 g quantity f h lti modified line inorganic powder has an average particle powder was charged to a 10 liter pot mill and crushed diameter of 01-15;; and is admixed with said polyolein air at 20C for 48 hours at the rate of 50 rpm. The fin resin to prepare a non-stretched film. powder was then dried for 1 min. at 350C to yield a 4. The resin composition of claim 1, wherein said modified fine powder with an average particle diameter modified inorganic powder with an average particle diof 40 mu. In accordance with the preparation of Examameter of 0. l-l5 J. is admixed with said polyolefin resin ple 4, a biaxially stretched polypropylene film was preto prepare a non-film article. pared using the modified fine powder. The properties 5. The resin composition of claim 1, wherein said of the resulting film are shown in TABLE VI. modified fine inorganic powder has an average particle TABLE VI No. Fine Ca CO3 Melt Melt Cloudi- Block- Coefficient powder index index ness ing of static pellet film )Haze) property friction (g/lOmin) (g/lOmin) (g/l0cm")- Reference 1 Unmodified 1.4 2.4 1.8 350 0.55 Invention 2 Modified by 1.3 2.3 1.0 390 0.58

' Ida-stearate Having now fully described the invention, it will be apparent to one of ordinary skill in the art that many diameter of 300-10 my. and is admixed with said polyolefin resin to prepare a biaxially stretched film. 

2. The resin composition of claim 1, wherein said inorganic powder is admixed with 0.1-30 weight percent of said surface modifier based on the weight of said inorganic powder, and wherein said polyolefin resin is admixed with 0.01-2.0 weight percent of said modified fine inorganic powder based on the weight of said polyolefin resin.
 3. The resin composition of claim 1, wherein said modified fine inorganic powder has an average particle diameter of 0.1-15 Mu and is admixed with said polyolefin resin to prepare a non-stretched film.
 4. The resin composition of claim 1, wherein said modified inorganic powder with an average particle diameter of 0.1-15 Mu is admixed with said polyolefin resin to prepare a non-film article.
 5. The resin composition of claim 1, wherein said modified fine inorganic powder has an average particle diameter of 300-10 m Mu and is admixed with said polyolefin resin to prepare a biaxially stretched film. 